1. Field of the Invention
The present invention relates to a light emitter driving device that drives a light emitter such as an LED (light emitting diode) and the like, and to a lighting appliance that uses the light emitter driving device.
2. Description of Related Art
In recent years, various LED driver ICs compatible with a TRIAC (bidirectional thyristor) dimming method are put in practical applications. The TRIAC dimming method is a dimming method that has been conventionally employed as a dimming method for an incandescent lamp and the like. Accordingly, if an LED driver IC compatible with the TRIAC dimming method is used, it becomes possible to perform dimming of an LED lighting appliance by using an existing TRIAC dimmer.
Here, as an example of the conventional technology related to the above description, there is JP-A-2010-73689.
Here, a TRIAC dimmer has a structure in which malfunction occurs if a hold current having a predetermined value or more is not flowing. FIG. 11A to FIG. 11C are each a view showing an output waveform from the TRIAC dimmer. Here, FIG. 11A shows an output waveform during a usual time, FIG. 11B shows an output waveform during a phase angle trouble time, and FIG. 11C shows an output waveform during a frequency trouble time.
For example, as shown in FIG. 11B, in a case where a phase angel trouble occurs in the output waveform from the TRIAC dimmer, brightness of an LED changes unintentionally, whereby a flicker occurs. Besides, for example, as shown in FIG. 11C, in a case where a frequency trouble occurs in the output waveform from the TRIAC dimmer, the LED repeats unintentional on/off, whereby a flicker occurs. FIG. 11B and FIG. 11C each exemplifies an overview in which the above trouble suddenly occurs during a period T; however, there is also a risk that the above trouble could occur constantly over a plurality of the periods T.
Here, in the conventional LED driver IC, as a measure against the malfunction of the TRIAC dimmer, a bleeder circuit for keeping the hold current of the TRIAC dimmer and an RC filter for applying a filter process to the output waveform from the TRIAC dimmer and the like are externally connected; however, it is hard to completely remove the flicker from the LED.